The big question this fall was: Why did corn and soybean yields in general turn out better than many expected after a very dry August? At least one agronomist believes part of the answer lies in the favorable weather leading up that point, including relatively cool temperatures at night during key parts of the growing season.
"The cool temperatures at night let plants rest and fill the pods more slowly," says Mary Gumz, a DuPont Pioneer production agronomist who works in northwest Indiana. She places considerable value on the cooler nighttime temperatures this year.
Last season brought not only heat, but high nighttime temperatures. The past several seasons have featured relatively high nighttime averages in Indiana during the key reproductive periods. In several of the preceding years before this one, the USDA estimated yield dropped from the initial estimate through the final report later in the year. Some believe that high nighttime temperatures contributed to that result because corn or beans weren't filled as well as most expected them to be. The opposite was true this year.
Ken Scheeringa, associate state climatologist in Indiana, provides data that shows temperatures were on the cooler side at night compared to the past few seasons. It's not proof that the lower temperatures provided a plus for crops, but it does show that the temperatures averaged a few degrees lower per night in this past season compared to several other recent seasons.
Scheeringa calculates state monthly averages for nighttime lows just for this exercise. Here's what he found:
Note the much lower temperature for July in 2013. Also note that in 2012, soybeans ran ahead of schedule, and early to mid-season varieties were in the reproductive mode in late July to early August, when temperatures were still warmer, and before rains brought relief to some areas.